[Bug]: Short description of the issue

[R1YMOLIM]

Hello guys i'm configuring conf.nix and get this error help me pls!

┌─[r1y@NixOS] - [~] - [Sat Dec 07, 23:50]
└─[$] <> sudo nixos-rebuild -I nixos-config=/home/r1y/NixOS-Hyprland/hosts/NixOS/config.nix switch

building Nix...
building the system configuration...
error:
… while calling the 'head' builtin
at /nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/lib/attrsets.nix:1574:11:
1573| || pred here (elemAt values 1) (head values) then
1574| head values
| ^
1575| else

   … while evaluating the attribute 'value'
     at /nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/lib/modules.nix:846:9:
      845|     in warnDeprecation opt //
      846|       { value = addErrorContext "while evaluating the option `${showOption loc}':" value;
         |         ^
      847|         inherit (res.defsFinal') highestPrio;

   … while evaluating the option `system.build.toplevel':

   … while evaluating definitions from `/nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/nixos/modules/system/activation/top-level.nix':

   … while evaluating the option `assertions':

   … while evaluating definitions from `/nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/nixos/modules/system/boot/systemd.nix':

   … while evaluating the option `systemd.services':

   … while evaluating definitions from `/nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/nixos/modules/services/logging/logrotate.nix':

   … while evaluating the option `services.logrotate.enable':

   … while evaluating the option `users.groups':

   … while evaluating definitions from `/nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/nixos/modules/config/resolvconf.nix':

   … while evaluating the option `networking.resolvconf.enable':

   … while evaluating the option `environment.etc':

   … while evaluating definitions from `/nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/nixos/modules/services/networking/ssh/sshd.nix':

   … while evaluating the option `users.users':

   … while evaluating definitions from `/home/r1y/NixOS-Hyprland/hosts/NixOS/users.nix':

   … while evaluating the module argument `username' in "/home/r1y/NixOS-Hyprland/hosts/NixOS/users.nix":

   (stack trace truncated; use '--show-trace' to show the full, detailed trace)

   error: attribute 'username' missing
   at /nix/store/nr5nl3zwzl02x3rnikjbry3s5xy7bm1d-source/lib/modules.nix:515:28:
      514|         addErrorContext (context name)
      515|           (args.${name} or config._module.args.${name})
         |                            ^
      516|       ) (functionArgs f);

┌─[r1y@NixOS] - [~] - [Sat Dec 07, 23:58]
└─[$] <>